Preheat the oven to 350 degrees F. Spray a 9 x 13-inch baking dish with non-stick cooking spray. Add the rice to the bottom of the baking dish.
Cut the chicken breast into bite size pieces.
Melt butter in a skillet and add the onion. Cook the onion until tender 2 or 3 minutes. Add the flour and stir in. Add the chicken broth and cream and cook until it starts to thicken.
Add the chicken to the rice and top with the frozen vegetables. Pour the sauce over the ingredients in the baking dish.
Cover with aluminum foil and bake for 30 minutes. Remove from the oven and remove the aluminum foil. Sprinkle the French fried onions over the top of the casserole and bake for another 15 to 20 minutes